With an upper respiratory bug sweeping through the team that already is dealing with assorted ailments, the Knicks had just four bodies in shape to participate in a regular practice Wednesday, according to coach Mike Woodson. So players, who did not fully practice, did whatever they could.

Raymond Felton, one game back from a groin strain, Amar’e Stoudemire and Iman Shumpert did some shooting while Tim Hardaway Jr., Toure’ Murry and Jeremy Tyler did some contact work.

“A lot of guys are sick. I think everybody came in and did something. Not everybody was able to go out there and practice. But everybody did something,” Shumpert said. “Some guys were in the weight room. Some guys were getting treatment. Some guys were shooting. Some guys were riding bikes. Everybody was doing something.”

With Kenyon Martin, Andrea Bargnani and Cole Aldrich joining Tyson Chandler on the upper respiratory infection list, the Knicks’ best weapon against the Heat Thursday might be breathing on them.

“We’re a little beat up from a health standpoint. I didn’t have much to work with [Wednesday] because there’s a bug going around our team and a lot of guys are under the weather a little bit so we’ve just got to maintain,” Woodson said. “The guys that are going to dress tomorrow, who that might be I don’t know at this point.”

Woodson said he liked what he saw from Felton in the point guard’s return Tuesday from a strained groin. Of course, Beno Udrih’s knee acted up and he sat the second half and Pablo Prigioni remains out with a fractured toe.

“I thought he did some good things for us but he labored a little bit still, the fact that he hadn’t been out there,” Woodson said of Felton. “We spoke a little bit today and he was a little sore. He was out getting shots up. Some of the things he’s going through we expected because he was sitting so long.”

Udrih was expected to go for an MRI exam on his sore knee, making him “probably questionable because he couldn’t go … in the second half [Tuesday], based on his knee.”

The biggest change in the Knicks? Defense.

“We’re playing better as a ball club, especially on the defensive end. Our numbers indicate that over the last four games,” Woodson said. “But again, it’s been tough for our team this season. I think No. 1 because we haven’t been able to really practice and put guys in position from a defensive standpoint and really knowing rotations every time they step out on the floor.”

The last two games — wins over Dallas and Detroit — have seen the Knicks surrender just 80 and 85 points, respectively. Over the four games Woodson referenced, the Knicks have yielded an average of 92.0 points and allowed 42.9-percent shooting (135 of 315). More importantly, they’ve won three of the four games.